#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/io.h>
#include <sys/types.h>
#include <fcntl.h>

#define BASEPORT 0x378 /* lp1 */

int main() {
   char c;
   int n, tem;

   printf("Hit Enter key to stop\n");

   //set permissions to access port
   if (ioperm(BASEPORT, 3, 1)) {perror("ioperm"); exit(1);}

   tem = fcntl(0, F_GETFL, 0);
   fcntl (0, F_SETFL, (tem | O_NDELAY));

   //main loop where actual blinking is done
   while (1) {
       //if Enter key is pressed, break out from loop
       n = read(0, &c, 1);
       if (n > 0) break;

       //write 'on' bit on all data pins and wait 1/4 second
       outb(255, BASEPORT);
       usleep(250000);

       //write 'off' bit on all data pins and wait 1/4 second
       outb(0, BASEPORT);
       usleep(250000);

              //if Enter key is pressed, break out from loop
              n = read(0, &c, 1);
              if (n > 0) break;
   }

   fcntl(0, F_SETFL, tem);
   outb(0, BASEPORT);

   //take away permissions to access port
   if (ioperm(BASEPORT, 3, 0)) {perror("ioperm"); exit(1);}

   exit(0);
}